ITEM 415 - ELASTOMERIC, HOT-APPLIED JOINT SEALANT WITH SINGLE-SIZED AGGREGATES FOR BRIDGE EXPANSION JOINTS

415.1 Description

This Item shall consist of furnishing and placing elastomeric, hot-poured joint filler with single-sized aggregates in bridge expansion joints in accordance with this Specification and as shown on the Plans, or as directed by the Engineer.

The joint filler combines an elastomer modified bitumen binder and selected single-sized aggregates for the strength and flexibility of the joint. It accommodates up to ±25 mm movement in horizontal direction but it can move in all directions. The joint is constructed in-situ and is a hot process.

415. 2 Material Requirements

415.2.1 Bituminous Materials

The binder is an elastomer-modified bitumen, formulated to combine good fluidity for the installation process and flexibility with the following properties:

Properties	Requirement	Test Method
Softening point, 0C (Ring & ball method) Flow resistance @ 600C, mm Cone penetration @ 250C, 150g, 5 sec.; dmm Safe heating temp. 0C Pouring temp, 0C Safe heating time, hr.	95 to 115 5 max. 10 – 30 220 max. 190 to 210 7 max.	ASTM D 36 or AASHTO T 53 ASTM D 1191 or AASHTO T 187

415.2.2 Aggregates

Aggregates are single-sized stones normally chosen from the Basalt, grit stone, gabbros or granite group. The use of a single aggregate enables a higher binder content to be reached. It will also ensure a constant ratio of stone to binder. This is important to give the joint its optimum combination of flexibility and load bearing capacity.

Joint Depth	Stone Size
50 mm to 75 mm 76 mm to 100 mm	14 mm or 20 mm 20 mm

415. 2.3 Caulking - Premolded expansion joint filler (sponge rubber type) conforming to AASHTO M 153.

415.2.4 Steel Plate - Use appropriate size of plate based on plate selection table. Material shall be A 36 conforming to AASHTO M 270.

415.3 Construction Requirements

The binder fills the gap and the voids between the single sized aggregates. Its purpose is to impart flexibility to expansion joint so that it accommodate the various movements of bridge.

415.4 Installation Procedure

1. Layout - In case the trenches are not preformed, joints are laid out on the site by locating the exact gap opening and measuring 250 mm on both sides from the center of the gap. The center of the layout shall be the center of the gap. Chalk-mark both sides of the joint width. Cut the full depth using a concrete cutter. A strict minimum of 50 mm depth is observed, in cases where there is wearing course and the thickness is less than 50 mm, the deck shall be chipped upon the approval of the bridge engineer to attain the required minimum depth. After cutting the full depth of the joint, break the joint location by using a jackhammer. Remove all broken slabs to open a trench. The side wall shall also be free from loose debris and shall at least be at right angle with the exposed deck.

2. Cleaning - Clean the trench thoroughly by using compressed air to remove all visible dusts. It is best wire-brush the sides of the trench as well as the de remove all loose particles.

3. Installation of Premolded Joint filler - Install a compressible premolded rubber type joint filler on the trench gap. Make sure that the premolded expansion joint filler was installed approximately 25 mm below the deck level at 25% minimum compression to allow the binder to fill the top portion and prevent from falling.

4. Hot Air/Flame Cleaning/Pre-heating - The trench is then cleaned and pre-heated by using hot compressed air. This shall remove all remaining debris and will completely clean and heat the trench to prepare it for priming.

5. Priming - Heat the binder to its working temperature of 190°C to 210°C. When the binder is ready for use, prime the trench with the binder. Ensure that all surfaces are evenly covered with binder. Ensure that the top of the premolded expansion joint filler is also filled with binder up to the deck level.

6. Plating -Cover the top of the gap. Position the plate cover on the center of the gap and fix it with locating pin. In small joint gaps, the primary purpose of the plate is to prevent the binder from continuously flowing to the gap during priming. However, in case where the joint gap exceeds 30 mm in width, the plate shall be of importance to distribute vehicular loading.

7. Plate Priming - Pour binder on top of the plate and ensure that all the surface of the steel plate, including its sides are covered with binder.

8. Stone Laying Prepare the pre-washed aggregates (normally gabbros or granite family), by putting it inside a mixing tub. Heat the aggregates while the tub is rotating until it reaches the working temperature of 150°C to 180°C.

A premix of one layer of aggregates can be put in the trench. Rake the aggregates to spread it evenly on the trench. Make sure not to lay the stone more than 25 mm thick per layer.

Aggregates size are normally 14 mm or 20 mm in diameter, depending on the size of the joint, pre-washed, clean and packed in 20 kg to 23 kg.

9. Binder Pouring - Pour the binder on top of the stone layer. Rake the stones to spread it evenly on the trench. Ensure that each stone is covered with binder and the aggregates are in contact with each other. Pour binder to the trench and repeat stone laying and the binder pouring process until the stone and binder layer are approximately 20 mm to 25 mm below the wearing surface.

10. Topping - Prepare a premix of binder and stone in the tub on a 6:1 approximate proportion. Keep the mixing tub rotating while pouring the premix inside the tub. Make sure all aggregates are suitably covered with binder. Pour the premix on top of the joint to a level of approximately 20 mm above the wearing surface.

11. Compaction - Wait for the temperature to drop about so0c, then, using a vibratory plate compactor, compact the finished expansion joint to level the joint with the wearing surface. Make multiple passes to ensure that the joint is properly compacted. This will prevent the joint from setting on the later stage after opening to traffic.

12. Top Screed Surface - After compaction, prepare a binder topping and pour the heated binder on top of the compacted joint. Wearing a heavy-duty heat resistant hand gloves, manually screed the topping. Avoid too thick binder topping (recommended thickness is about 2 mm to 3 mm) and ensure that there are visible signs of stones after finishing the top screed. The top screed binder shall also serve as the waterproof top surface.

13. Cleaning -Clean the surrounding area and pour water on the finished expansion joint. Allow to cure to about 15 to 30 minutes depending on the ambient condition of the surrounding. The road could be immediately opened to traffic after cooling.

415.5 Method of Measurement

The installed expansion joint will be measured by the cubic meter (m³). The quantity to be paid for shall be the volume in-placed as shown on the Plans and accepted by the Engineer.

415.6 Basis of Payment

The accepted quantities, measured as prescribed in Section 415.5, shall be paid for at the contract unit price for the expansion joint which price and payment shall be full compensation for furnishing and placing all materials, including labor, equipment, tools and incidentals necessary to complete the work prescribed in this Item.

Payment will be made under:

Pay Item Number	Description	Unit of Measurement
415	Elastomeric, Hot­Applied Expansion Joint Sealant (with Single-Sized Aggregates)	Cubic meter